1. Field of the Invention
The present invention is generally drawn to remote monitoring devices and more particularly to remote monitoring of high voltage motor parameters.
2. Description of the Prior Art
It is known to have operators acquire motor electrical signal analysis data by connecting probes onto live electrical cables carrying voltages up to 600 volts RMS AC. In this process the operator would open the electrical cabinet door of the cabinet housing the motor control circuitry, connect three clamp-on current transformers and three alligator clips, acquire the data, disconnect the probes, close the door and move to the next motor cabinet to be tested. Thus, the operator constantly reached into potentially lethal voltages twice per motor to be tested. Some plants even refused to permit operators to reach into live cabinets and so no electrical signature analysis data could be obtained. Other plants permitted operators to reach into the cabinet if the operator were properly trained and if the operator wore prohibitively bulky and hot safety gear. This means that some plants which would not permit personnel to acquire motor data for safety reasons were running risks of disastrous failures.
An alternative known method involved acquiring current data only by connecting the current transformers to the power cables just prior to their being routed to or through cable trays or conduits. The same safety problems were found.
Certain other systems for monitoring high voltage motor performance and safety are known as shown in the following US patents.
U.S. Pat. No. 5,571,132 teaches the use of various high voltage motor phase and insulation monitoring systems having a tester connected to the motor power lines through relays to monitor the proper operation of the motor.
U.S. Pat. No. 4,787,244 teaches that it is known to enclose high voltage motor access ports within cases and provide quick connect cables to these motors.
U.S. Pat. No. 4,090,230 teaches that it is known to enclose high voltage motors within cases having external and internal doors for isolating dangerously high voltages from operators.
U.S. Pat. No. 5,652,526 teaches another type of high voltage motor performance testing system.
A review of these patents shows that there is no teaching of using an enclosure for the motor and placing a voltage reducing module neither in the motor case nor of using quick connects on the motor case to safely supply the monitored signals to a remote motor monitoring system to provide much needed safety in monitoring high voltage motors. The patents that do teach motor enclosures and quick connects fail to teach their application to a voltage reduction module in the enclosure and the quick connect internally and externally thereof. These are much needed safety features.